The present invention relates to a method of cleaning the surface of a photoconductive member in an electrostatic copying apparatus of the transfer type in which a polarizable magnetic toner is used as a developer, and more particularly to a method of removing residual magnetic toner from the photoconductive surface after the transfer of toner images.
Various cleaning methods are known for electrostatic copying apparatus in which a magnetic brush is used for a magnetic toner having a polarity as disclosed in Japanese Patent Application Disclosures No. 122938/1975, No. 76932/1977. These known methods mainly utilize the electrostatic attraction acting between the magnetic toner and the magnetic brush and produced by a bias potential having a polarity opposite to that of the toner and given to the brush, while utilizing an electrostatic repelling force produced between the surface of the photoconductive member and the toner by a charge having the same polarity as the toner and given to the photoconductive surface.
However, the polarizable magnetic toner for which the method of this invention is used is not removable in the same manner as in the conventional cleaning method for a magnetic toner having a polarity in which the polarity of the toner itself is utilized. Moreover, when the photoconductive surface is charged, the toner on the magnetic cleaning brush will be polarized again by the charge on the photoconductive surface and attracted to the surface. Thus the surface of the photoconductive member can not be cleaned.